Variable speed mechanism



Oct. 24, 1939. P. J. M LAREN VARIABLE SPEED MECHANISM Filad Aug. 20, 1937 10 Sheets-Sheet l INVENTQR 'Pefer J McLaren.

BY w? M ATTORNEYS Oct. 24, 1939. P. J. M LAREN VARIABLE SPEED MECHANISM 1o Sheeis-Sheet 2 Filed Aug. 20, 1937 mvENToR I P er J. McLaren. BY w 7 M ATTOR N EYSL Oct. 24, 1939. P. J. M LAREN 2,177,611

VARIABLE SPEED MECHANISM Filed Aug. 20, 1937 10 Sheets-Sheet i5 4 s I I l\ '\rg l INVENTOR Pefer J McLamn.

ATTORNEYS- Oct. 241- 1939. P. J. M LAREN 2,177,611

VARIABLE SPEED'MECHANISH Filed Aug. 20, 1937 10 Sheets-Sheet 4 INVENTOR Pefer J McLa/"m ATTORN EYS.

Oct. 24', 1939.

P. J. M LAREN VARIABLE SPEED MECHANISM Filed Aug. 20, 1957 10 Shoots-Sheet 5 R O T N E V m Pefer J. Mc Laren. BY @wad 1 @Zt ATTORNEYS.

10 Sheets-Sheet 6 P. J. M LAREN VARIABLE SPEED MECHANISM Filed Aug. 20, 1937 Q ,///z /v Oct. 24, 1939.

Pfer J. Mr; L are.

BY ATTORNEYS.

Q N1 R s Oct. 24, 1939. P. J. McLAREN VARIABLE SPEED MECHANISI Fi 1ed-Aug. 20, 1937 10 Shoots-Sheet '7 HNVENTOR Defer J McLaren.

. Oct. 24, 1939. P. .1. M LAREN VARIABLE SPEED MECHANISX Filed Aug. 20, 1937 10 Sheets-Sheet 8 INVENTOR Pefer J McLaren ATTORNEYS. v

Oct. 24, 1939. P. J. McLAREN 2,177,611.

VARIABLE SPEED MECHANISM Filed Aug. 20, 1937 10 Sheets-Sheet 9 w m m BY MVM ATTORNEYS.

Oct. 24, 1939. P. J. M LAREN VARIABLE SPEED MECHANISM Filed Aug. 20, 1937 10 Sheets-Sheet 1O INVEN1 UK. Pe fer McLa/"en. BY M9 Xgwwf ATTORNEYS.

Patented Oct. 24; 1939 UNITED STATES PATENT OFFICE vamanm srnsn YMECHANISM Peter J. McLaren, New York, N. Y.

' Application August 20, 1931, Serial N- 160,052

22 claims. (01. 14-283) This invention relates broadly to multiple speed transmission mechanism, and more particularly to mechanism or a kind adapted to provide a very large number of transmission ratios. An apl paratus of the kind referred to may, for example,

comprise an input member adapted for progressive operation to any desired extent, an output member operable from the input member, a multiple speed transmission means, and a transmis- 10 sion ratio selector for establishing any one of a multiplicity of available driving ratios from the input member to the output member.

In accordance with known practice, a. common input member is arranged to be coupled through 1 any one or more of a number of transmission channels with a common output member, the several channels being so constructedand arranged that their individual transmission ratios form the geometrical series 1k, 2k, 4k, 8k (is being a con- 20 stant). With these ratios available for use individually and in any desired combination of two or more, 15 transmission ratios are made possible whose relationship is such that the available ratios form the complete arithmetical series 26 1k, 2k, 3k 15k. A selector mechanism is Drovided for controlling the order of selection or coupling to cause the available ratios to be made effective, in continuously ascending or continuously descending order. These principles are deti? sirably adhered to in the present invention.

In prior practice, the principles referred to have been susceptible of very limited application. Each transmission channel includes a primary gear on a common input shaft, which gear is adapted to be coupled to and uncoupled from the shaft by the selector mechanism, and a secondary gear in mesh with the primary gear and bearing a size relationship to the primary gear suitable to establish the characteristic ratio of so the channel. The outputs of adjacent pairs of secondary gears are combined through differen tial gears, and the outputs of these differential gears are in turn differentially combined for transmission to the common output member.

45 Such a construction is expensive in a simple case because of the necessity for providing distinctive' primary and secondary gears. The more serious objection, however, lies in the fact that any attempt to extend the application of the 5d underlying principle would involve making the ratio of the primary gear to the secondary gear of each added channel twice as great as the ratio of the primary gear to the secondary gear of the channel which precedes it in the series. The provision of gears bearing a ratio to one am other of 256 to l, for example, would involve the employment of a very large gear and, because of the necessity for leading all of the channels through difl'erential gearing to a common outlet, would necessitate the enlargement of gears and 5 other parts all along the line.

Similar objections occur in connection with the selector mechanism heretofore employed.

Such selector mechanism includes a series of cams affixed to a common selector shaft for rotation 10 in unison, each cam controlling the coupling and uncoupling of a single one of the channels in its proper order to cause the transmission ratios successively made available to form an unbroken arithmetical series. The channel of the lowest individual transmission value must be eflectiv for each odd ratio and ineffective for each even ratio. If, therefore, there are 15 available ratios, the cam must have 8 high spots and 8 low spots in regular alternation, which is feasible, but if there are to be 51 available ratios the cam must have 256 high spots and 256 low spots in regular alternation, which is possible only in a construction of enormous size.

It is a primary object of the present invention 28 to provide a multiple speed mechanism which may be made compactly and economically, and which is practically capable of extension over a greatly increased range of transmission values as compared with prior structures. The inven- 30 tion involves important features of novelty both in the transmission mechanism itself and also in the selector mechanism.

In accordance with a practical and highly advantageous feature of the invention, a series of 36 like differential gears is provided, the gears being mounted coaxially upon a common shaft. Each differential includes a primary input gear arranged to be individually coupled to and uncoupled from a common input or operating shaft 40 and to be locked against operation when uncoupled. Each difierential gear other than the last in the series includes an output gear through which it transmits its entire input, divided by two, to a secondary input gear of the next dflferential gear higher in the series. The last difl'erential gear of the series includes an output gear which operates a common output shaft; that is to say, the entire input to all of the differential gears is transformed and transmitted W through the output of the last differential gear. The first diirerential gear of the series has but one real input, its secondary input being always looked against operation.

Thus an input through the primary input gear of the first differential gear passes through all of the differential gears and is cut in half once for each differential passed through. The individual input value of the first differential gear may be called 1. An input through the primary input gear of the second differential is also cut in half once for each differential passed through, but since it passes through one less differential gear than the input through the first differential gear, it is cut in half one less time. The individual input value of the second differential gear is twice as great as the individual input value of the first and is, therefore, 2. Similarly, the individual input value of the third differential is 4, that of the fourth is 8, and so on.

Broadly, the invention contemplates the provision of a set of transforming differential gears adapted for selective coupling in parallel through their respective primary input gears to a common rotary input member, and permanently connected in series through their output gears and their secondary input gears to a common rotary output member.

The differential gears may all be exactly alike in construction. There is, therefore, no necessary limitation upon the number of transmission ratios which may be made available. Since the several differential gears may all be duplicates. moreover, the construction is inexpensive as compared with prior practice. The gears may be of moderate size and the arrangement may be very compact.

The order in which the primary input gears of the several differentials are required to be coupled and uncoupled in order to cause the successively available transmission ratios to form an unbroken arithmetical series may be briefly indicated. The primary input gear of the first differential should be out of action for zero, in for 1, out for 2, and so on at alternate steps. The primary gear of the second differential should be out of action for zero and 1, in for 2 and 3, out for 4 and 5, and so on at alternate pairs of steps. The primary input gear of the third differential should be out of action for zero to 3, in for 4 to 7, out for 8 to 11, and so on at alternate sets of 4 steps. In other words, if the individual input value of a differential is represented by 2 power it should first be out for 2 steps, then in for 2 steps, and so on in regular alternation.

It is not inconvenient to provide a cam unit comprising three cams for controlling the primary inputs of only three differentials, since this requires only that the cam controlling the primary input of the first differential shall have four high spots and four low spots in alternation. A plurality of such units are provided. A full rotation of each unit requires a unit to be advanced through eight equal steps. Carry-over mechanism is provided for operating the second unit a single step at each eighth step of the first unit, and similar carry-over mechanism is provided for operating the third unit a single step at each eighth step of the second unit. The carry-over mechanism most desirably takes the form of Geneva gearing which positively locks each higher unit against operation at all times, save the particular step or steps during which it is required to be operated.

The specific arrangement indicated is, of course, to be regarded merely as illustrative, since the principle of providing a plurality of selector units each operated through carry over from a selector unit of lower order may obviously be put into practice in a variety of specific ways.

A selector mechanism constructed for operation in accordance with the principle outlined may consist of very simple and compact units which are duplicates of one another. A selector mechanism of this kind embodies no necessary limitation upon the number of speed ratios which may be made available.

The selector mechanism may be arranged to set up successive driving ratios which form an unbroken arithmetical series as described above, or to set up a broken or interrupted series if desired.

It is a further object of the invention to provide a transmission mechanism for utilizing the broad principle heretofore pointed out, but in which simple, internal, epicyclic, differential gears are employed. In simple gearing of this type it is not possible to cause each differential to divide its input by 2. A division by 4 is, however, possible. Pursuant to the attainment of the stated object, two banks of differentials are desirably provided, each differential constructed to divide its input by 4, and each connected through its neighbor higher in the series to a common output shaft. The common output shafts of the respective banks are so connected to a final output shaft which is common to the two banks that one bank in its entirely has twice the weight of the other. Thus the differentials in one bank may have individual output values of 1, 4, 16, 64, etc., while the differentials of the other bank may have individual output values of 2, 8, 32, 128, etc., the two banks together providing individual output values representing each power of 2.

Other objects and features of the invention will appear as the description of the particular physical embodiment of the invention selected for illustration thereof progresses.

In the accompanying drawings, like reference characters have been applied to corresponding parts throughout the several views which make up the drawings, in which:

Fig. l is a plan view of a speed changing mechanism in the construction of which the present invention has been embodied;

Fig. 2 is a View thereof in side elevation, look ing from right to left on Fig. 1;

Fig. 3 is a view in vertical section, taken on the broken line 3-3 of Fig. 1;

Fig. 4 is a view in rear elevation of the mechanism shown in Figs. 1 and 3 with the rear plate removed;

Fig. 5 is a view thereof in front elevation with the front plate removed;

Fig. 6 is a fragmentary detail view in section on the line 6-8 of Fig. 3;

Fig. 7 is a fragmentary, on the line 'l-'! of Fig. 3;

Fig. 8 is a fragmentary detail view in vertical section on the line 8-8 of Fig. 6;

Fig. 9 is a fragmentary detail view showing separately and on an enlarged scale one of the spiders of a differential, with its associated parts;

Fig. 10 is a schematic view in perspective of the several instrumentalities of the mechanism, assembled in their combinative relationship;

Fig. 11 is a similar fragmentary detail view in stretched-out perspective of one of the differential speed-changing devices of the mechanism, illustrating its connection with the adjacent differential of the series;

Fig. 12 is a diagrammatic view illustrating a modified form of speed changing mechanism;

Fig. 13 is a fragmentary horizontal sectional detail view in section casing, a gear i8 which in the side wall seen in Fig. 7,

view showing details of the structure diagram matically illustrated in Fig. 12; and

Fig. 14; is a fragmentary sectional detail view, taken on the line ll-il of Fig. 13,1ooklng in the direction of the arrows.

In the now preferred embodiment of this invention selected for illustration and description, the reference character C designates generally the casing of a speed changing mechanism, the casing being made up of front and rear plates H and I2, side plates I3 and H; also a bottom plate i5 and top plate members It and I61.

All of the mechanism, in the embodiment illustrated, is organized in connection with several shafts disposed in axial parallelism between the side walls or members l3 and H, in which suitable bearings are provided which are not illustrated in detail as they may be of any sutable construction. A shaft designated 20 constitutes the main driving member of the mechanism and is hereinafter referred to as the input or driving member or driving shaft. This shaft is provided with several pinions 2| to 29 inclusive (see Figs. 3, 5 and 10), each pinion serving to impart input motion to one of a series of speed changing devices of which there are nine in the instance illustrated, although any suitable number may be provided, in accordance with the needs of any particular installation. The driving member 20 may be actuated by any suitable means, and in the instance shown such actuation is illustratively provided for by a handle IS.

The handle is shown at the left hand side of Fig. 1, but the power may be supp ied from the other side with equal facility. The reference characters D|-D9 in Fig. 5 and F g. 10 designate respectively each a speed changing mechanism constituted by a differential. Each differential includes a spider (see Figs. 3, 5, '7, 9 and 11) of which there are nine, designated M49 inclusive, each being fixed upon a hub 9 -(see F gs. '7, 9 and 10), mounted upon a driven shaft 30, the driven shaft being common to the entire system of differentials, in the instance illustrated, and having at its end (see Fig. 5) beyond the boundaries of the serves illustratively as means to deliver the comb ned output motion of the speed changing mechanism as a whole.

Upon further reference to Fig. 'I, it will be seen that the driven shaft 30 has fixed thereto. as by a pin Hi, the hub 9a: of the spider 39, this being the last in order of the series of spiders, the first of which, 3i, forms part of the differential DI. illustrated in detail in Fig. 9, while the first four differentials, and their associated parts. are shown in a perspective assembly view in Fig. 10.

All motion communicated to the driven shaft 3!] is delivered thereto through the spider 39, the hubs 9, see Fig, '7, of all of the other spiders being freely mounted relatively to the shaft 30. The rotative motion of every spider, and of each differential, is developed with respect to a stationary gear 1?! of the differential Di, fixed at P H of the casing, and which serves as a sun gear for a planetary pinion ll mounted on an arm H of the spider 3| (see Figs. 9 and 11) A planetary pinion 4 la: is carried by an arm "a: of the spider, and is in mesh both with the planetary gear 4i and with a gear 5|: which forms part of a Siamese or. duplex, primary input gear 5i to 5k: having a common hub 50, best and in Fig. 10, where this duplex gear is shown as mounted rotatably on the hub 9 of the spider 3i. Integral with this hub 9 is the secondary'input member P2 of the next differential D2 in the series, and the same arrangement continues throughout the series of differentials, each comprising a structure including a spider, with its planetary pinions, the spider hub with the secondary gear of the adjoining differential, 5 and the duplex or primary input gear rotatably carried therebetween on the spider hub.

This structure is clearly shown also in Fig. 11, which illustrates also in schematic fashion the relationship between the driven shaft 30 and the 10 surrounding hub 9 of the spider, extending through the hub 50 of the duplex gears 5|--5|x, to the secondary input member P2 of the differ- I entlal D2.

'In pursuance of the invention, provision is 15 made of a series of coupling gears (see-Figs. 10, 11, etc.), numbered 61 to 69 inclusive, of which one is provided for each of the differential speed changing mechanisms, and each of these coupling gears is always in mesh with the primary 2o 4 input gear 5|--59) of its particular'diiferential, as'shown in Fig. 10, where all of the coupling gears 6| to 64 are in mesh respectively with their complemental primary input gears 5| to 54 inclusive.

'ch coupling gear'is mounted rotatably, as at Ola, etc., upon a rocker of a series Rl to R9, pivoted upon a shaft (seeFig. 4). These rockers are spaced apart by blocks Rx. The gears "-69 are prevented from rotating when in their 30 non-driving positions by detent spring Sac. Since the gears |i|-G9 are constantly in mesh, respectively, with the gears 5|-59 of the differentials D|-D9, each of the gears 5|-59 is locked against rotation whenever it is not coupled with 5 the associated one of the pinions 2| to 24 on the driving shaft 20.

In further pursuance of the invention a selector means is provided for each differential and is adapted to move each coupling gear of the series 40 Bl-GQ into and out of mesh with the corresponding pinion of the series 2|--29 on the driving shaft.

This movement of each coupling gear is effected through its corresponding rocker of the 5 series Rl-RS, and a series of springs S| to S9, is provided, each of which bears against a rocker intermediate its pivot point and the stud upon which the carrier is mounted, tending to bias each carrier toward the position in which it is coupled so with its corresponding pinion of the series 2|29 on the driving shaft.

Means to be now described are provided for the purpose of incapacitating'any of the differential speed changing mechanisms when the same is not required to he used in delivery of a selected rate of speed.

The preferred selector means comprise a cam shaft 10, Figs. 3, 4, 6 and 10, having thereon cams numbered 1| to 19 inclusive, taking the form of 60 radial discs having peripheral cam surfaces of characteristic shapes. For example, the cam ll isapproximately square but has at a, b, c and a1 cam surfaces which constitute the high spots of 65 the cam and correspond roughly with the posi= tions of the angles of a quadrangle, slabbed off.

Between c--b, b-c, c-d; and d-a; are the lower points of the cam II which, in the instance illustrated are designated respectively e, i, g, and 7o 11.. These intermediate low spots may be of any suitable shape, and are shown as slightly arcuate.

In Figs. 3 and 10, the high spot 17 of the cam II is shown as engaged with the nose at of the rocker Bl, with the result that the coupling gear II is positively retracted from the gear 2| on the driving shaft 28.

This position of the rocker RI and its coupling gear 8| is characteristic of all the gears not in use for delivering a selected speed, and it so happens that in the instance of the illustratively selected speed ratio 2-512, only the gear 62 is coupled to its corresponding actuating gear 22 on the driving shaft 28.

There is shown clearly in Fig. 10 of the drawing and does not require further description, so that it need only be added that the cams I2, 13, 14, etc., to 18 inclusive, operate in similar fashion upon the corresponding rockers, to incapacitate them when not required. Accordingly, the selection is negative as to all differential speed changing mechanisms not required, and those in use are spring-biased to operative coupled position, by the springs SIS9, as already described.

It will be observed that the cam I2 differs in shape from the cam II in the respect that it is of a generally oval shape, and only has two high spots x! and x2 and two lower spots yl and 3 2. In the instance illustrated, the rocker R2 has its nose n2 engaged with the low spot yl of the cam 12.

It will be observed further that the cam 13 has a still different shape, viz., it has a periphery with one high spot zl and one low spot 22. In the instance illustrated, the rocker R3 has its nose n3 engaged with the high spot zl of the cam 13 and is thereby held with its gear 63 away from the driving gear 23 onthe shaft 28.

Attention is now called to the fact that desirably the cams on the cam shaft are divided into groups or units, and in the instance illustrated, the cams ll, 12 and I3 constitute a unit which is what may be designated the first unit of the series of cams. The cams I4, 15 and 15 (see Fig. 6) constitute a second unit; and the cams ll, 78 and I9 constitute a third unit; there being three groups of cams or cam units in the instance illustrated, each succeeding group being a duplicate of the first group; With this number of units, having nine cams, it is possible to provide readily for a maximum of 511 combinations of gears, or rather selections of speeds, and this happens to be the number desired in the illustrative example herein shown.

Reverting to the first cam unit, it is noted that the cams H, 12 and 13, are mounted on a member 83, with which they may be integral, as shown best in Fig. 6, and the member 83, for the sake of brevity, will be designated a cam-sleeve, and it will be understood that each group of cams is mounted on a similar sleeve as at 84 and 85, so that these sleeves need not be further described in detail.

In addition to the cams upon each sleeve there is provided upon the sleeves 83 and 84 respectively a member which constitutes part of a carryover mechanism by which the unit represented by sleeve 84 is at times connected with the sleeve 83, and the sleeve 85 is at times connected with the sleeve 84, for the purpose hereinafter set forth.

In the instance illustrated, the carry-over mechanism is of a known type, in its'general com position, and includes a'driver 83 which by its peripheral surface 94 normally locks the transfer pinion element 9| by engagement between the teeth 9|, which are formed as lateral extensions of alternate teeth of an eight-tooth pinion 882:; these last-named teeth being disposed in alignment with the path of a segmental rack 88 which the medium of gear 8!.

is seen in Fig. 10 through a gap 92 in the carryover member 83 to which it is secured.

The rack 88 and pinion 88.2: being thus meshed intermittently, at such times the short transfer shaft 8'! is rotated, during the setting of the camshaft, and the pinion 88 at the other end of the short shaft 81 causes rotation of the full-toothed gear 88 on the sleeve 84, acting to carry-over into the second unit a setting rotation which is a suitable complement of the setting action initiated in the first unit.

By the above described means, the first sleeve 83 is adapted to be rotated for the greater part of its rotative orbit, independently of any of the other cam units, and the latter derive their own rotary movement only from the first cam unit, and only at such times as the interrupted gear 88 is in mesh with the complemental interrupted gear 86a: on the short shaft 81. In the instance illustrated, the segmental rack 86 is shown as having four teeth and the pinion 85:: as having four looking teeth SI and eight operating teeth 88.1, while the pinion 88 has eight teeth and the gear 89 has thirty-two teeth.

Accordingly, the second sleeve 84 will be rotated one-eighth of a turn for each complete rotation of the member 93 with its four teeth 86, associated with the first group of selector cams, and. during rotation of the non-active portion of the member 93 the short shaft 81 and consequently the sleeve 84 and its earns l4, l5 and 18, are maintained inactive. The member 93 and its associated elements constitutes a Geneva lock.

In the instance illustrated, there are two short carry over shafts, viz., 81 and 812: (see Fig. 4) so that what has been said with respect to the coupling of the sleeve 83 to the sleeve 84 is to be understood as applying to a similar coupling effect between the sleeve 84 and the third sleeve 85. In other words, at times the sleeve 85 and its associated cams derives its actuation from the sleeve 83 through the sleeve 84 and through the coupling shafts 81 and 812:; while at other times only the sleeves 83 and 84 are rotated and the sleeve 85 remains inactive.

In the operation of the mechanism as a whole, the selector cam shaft 18 will first be set to yield the desired speed ratio, as for example, 2:512, such setting being accomplished by any suitable Ii, I2 and I3 of the counter I which constitutes the indicator in the instance illustrated and described.

In the operation of the mechanism for the purpose first of setting it to the selected speed ratio, the rotation of the hand wheel H turns the pinion 88 secured to the shaft 48 and thereby rotates the gear 82, mounted on the cam shaft 18, through When the digits disc II of the counter stands at 2", as shown in Fig. 1, the cam shaft 18 will have been turned to the position shown in Fig. 10 with the cam 12 rotated, as illustrated, so that the nose 112 of the rocker R2 will be pressed by the spring S2 against the low surface ill of the cam I82 and consequently the carrier coupling gear 62 will be engaged with the pinion 22 on the driving shaft 28.

Accordingly, the gear 82, which is constantly in mesh with the pinion 52 on the sleeve 58 of the differential D2, is thus coupled to transmit from the driving shaft 28 to the pinion 52 a moment of rotation which is characteristic of the ratio between the number of teeth on driving gear 22 and 7 you driven gear 52. The sleeve 56 connected co-rotatively with the gear 52 will communicate its rotation to the gear 52a: of difierential D2 which willin turn rotate the planetary pinion 42a: and planetary pinion 42. The last mentioned planetary pinion is in mesh with the secondary input gear 19?. upon the sleeve 9 of differential DI, and inasmuch as the coupling gear 8| is in its incapacitated position, shown in Fig. 10, duplex or primary input gear iii-51m will not be driven by the shaft 2|; through coupler ill, but will be locked against rotation by the action of the detent spring Since the gear Pi is a fixed gear which never turns, the spider 2| is locked by the locking of the gear 5i-5|:c. The gear P2 is, as a consequence, locked against rotation, so that there is no input to the spider 32 from P2 and no outlet from the spider 32 through P2.

The pinion .52 will be rotated positively by the coupling gear 32, and its duplex pinion fizmwill rotate with it; this will rotate the planetary pinion 22m and the other planetary pinion 12, both of which are mounted on spider 32. As the gear is locked against rotation the planetary pinion 22 will track around the pinion 22 which is fast on the hub of spider 3i (see 7), and cause the spider 32 to rotate in the same direction as, but at half the speed of the pinion and this rotation will be communicated to the hub 9 of spider t2 and passed on to the pinion P3 of the differential D3; then through the chain 0! gears in like order, each reducing the speed by half, the output motion wilL'finally be communicated by the dowel pin ill to the output shaft til and thence to the pinion (18, which will be turned at the ratio of 2 R. P. M. to 512 R. P. M. or the shaft driving shaft 21!. 7

Each of the spiders 3| and 39 has theoretically two possible inputs. in the case of spider 3|, however, the gear Pi being a fixed or stationary .gear, there is never actually any input to the spider 31 from the gear Pl. When two elements of a differential are locked the third is locked also. Since Pi is always looked, the locking of iii locks 3|. When the coupling gear BI is connected to drive 5|, however, the spider 3| is not locked but is turned at half the speed of the gear iii, so that the gear P2 turning in unison with the spider 3| is driven forward at half the speed or the gear 5|. Now, similarly, the input from the gear 62 through 52to the spider 32 would be transmitted to the gear P3 to drive the gear P3 at half the speed of the gear 52, if the gear P2 were locked. Since we are now assuming, however, that the gear P2 is not locked, but that it is driven at half the speed of the gear 5|, the gear 1 P2 applies its input to the spider 32 and its input is just half that 01' the gear 52. The input of gear 192 is transmitted to drive 32, and hence gear P3, at half the speed of gear P2, and since the inputs of 52 and P2 are additively combinedby the spider 32, the gear P3 is driven at of the speed of the gear 52. Here again, the combination or" the inputs of P3 and 53, namely, and will be additively combined and divided by 2 in the transmission to P4, so that the resulting drive there would be 7 if n be taken as the number of difierentials, the numbers of available driving ratios is 2"- 1, and these ratios form an arithmetical series starting with 2 and terminating with All oi the rates of speed in the range from 1:512 to 511:512 can be secured by simple rotation of the setting wheel H to the various indicated positions shown at the counter I, in the illustrative embodiment of the invention.

Each position corresponding to the above indications upon the counter, is maintained by the action of a detent roller 99 mounted upon a detent arm 98 supported pivotally at 91 upon the side wall it or the casing, the arm 98 being biased. by a spring 96 to cause clockwise rota== tion of the arm 98 toward a star wheel 95 fixed 1 upon the cam shaft 10, best seen in Fig. 3. This star wheel has eight teethand eight spaces between the teeth, and when the star wheel is turned so that the detent roller 29 bears uni- -formly against the adjacent surface of anytwo oi" the teeth on the star wheel, the shaft it is held in such position that any selected cam disposed with one of the cam surfaces presented toward the nose of a rocker, as R2, standing in the plane of that cam.

in the instance illustrated in Fig. 3, the cam. '12, as already described, stands with its low spot y opposite the nose n of the rocker R2 and permits the carrier gear 62 to be forced by spring S2 into mesh with the driving gear 22 on the driving shaft 28.

In the form of construction illustrated in Figs.

12 to 14 inclusive, planetary difierential gears using internal gears are employed which may be made smaller and better balanced, and which are more economical to assemble, than planetary difierential gears using only external gears.

The structure embodies two banks of differential gears instead of one. The differential assemblies are all identical. The outputs oi the two banks are additively combined to make up the output of the unit as a whole. In the process of combining the outputs of the two banks the separate outputs are treated by gear ratios so that the output of one bank upon the combined output is twice that of the other.

The reason for employing two banks of differentials and for giving one bank twice the effect of the other arises from the type of difierential gears which are employed in this embodiment oi the invention.

it is not possible with planetary differential gears of the internal gear type, without using compound planetary gears, to make the step from lid one differential to the next in the ratio of 2-1,

it being necessary to make the step some ratio greater than 2-1. In the illustrated embodiment a ratio of 4-1 has been chosen. With each step representing a 4-1 ratio it is evident that if a value of 1 be given to the differential having the least effect upon the output, the successive 'differ entials of the same bank will bear relations to this first differential represented by successive powers of 4. Successive powers of 4 cannot be added to one another or combined in any way to give a continuous series including all integral numbers from 1 up to the sum of the several powers. For example, between 1 and 4 there is no way of securing 2 and 3. With 1, 4, 16 and 64 only 1, i, 5, 16, 1'7, 20, 21 etc., can be secured.

By providing a second similar bank, however, which starts with 2, values of 2, 8, 32 and 128 may be secured. Thus, by alternating between the two banks it will be seen that a difierential is provided representing each power of 2 from the zero power to the seventh power. The numbers of this series can be combined without using anyfig one of them more than once to secure any integral number from 1 to 255.

The differentials are all selectively driven from a common source represented illustratlvely by an input crank handle IOI which turns an input shaft I02. The input shaft carries the series of gears W2, W8, W32, and WI28 which may be coupled selectively, either simultaneously or separately, through transmission gears T2, T8, T32 and TI28 to drive internal gears I2, I8, I32 and II 28, respectively, which form elements of the differentials of one bank. The motion of shaft I02 is transmitted through bevel gears I03 and I04 to a cross shaft I05 and thence through bevel ears I06 and I01 to a shaft I08. The shaft I08 turns at the same speed but in the opposite direction from the shaft I02. The shaft I08 has fast upon it a series of gears WI, W4, WIS and W64 which may be coupled, respectively, through transmission gears TI, T4, TI6 and T64, to associated internal gears II, I4, II6 and I64 forming elements of the differential gears of the other bank. The object of the entire mechanism is to transmit motion at a selected rate or ratio from the shaft I02 to the output shaft I09 of the apparatus.

The rate selecting mechanism is illustratively shown as controlled from a finger wheel I I0 upon a shaft III which, through suitable gearing represented by II2, H3, and H4, drives a shaft H5. The shaft II5 has a series of cams I I6 upon it, each of different and appropriate contour, for controlling through a cam follower III the connection and disconnection of a' gear, as W2, on the shaft I02, with its associate internal gear, as I2, of the right hand bank of differentials. Only one cam is illustrated, and this diagrammatically. The shaft II5 acts through bevel gears H8 and III! to drive a shaft I20, and the shaft I20 in turn acts through bevel gears I2I and I22 to drive a shaft I23. The shaft I23 carries cams I24 for acting upon followers I 25, to connect and disconnect the differentials of the left hand bank with the shaft I08. One cam I24 is provided for each differential train and each cam may be of different contour, appropriate to the particular location of it in the machine. By providing a Geneva lock, however, a number of like groups of cams can be used as before.

If it be assumed that one revolution of the shaft I08 acting through the gear II imparts to the shaft XI a unit of revolution 1' then a single rotation of the shaft I08 will impart the same unit of revolution of rotation to the shaft X4 through the gear I4, to the shaft XI6 through the gear II6, and to the shaft X64 through the gear I64. Since one revolution of the shaft XI produces only A revolution of the shaft X4, however, and this same numerical relationship exists between the shaft X4 and shaft XI 6 and between the shaft XI6 and the shaft X64 a single revolution of the shaft I08 transmitted through the gear II will impart a: revolutions to the shaft XI revolutions to the shaft X4,

revolutions to the shaft XI6 and a revolution of the arm A64 revolutions to the shaft X64. Thus a single revolution of the shaft I08 transmitted through the gear I64 will produce 64 times as much angular movement of the shaft X64 as one revolution of the shaft I08 transmitted through the gear II and thence to the shaft X64 through the successive differential gears.

The right hand bank of differentials being identical with the other bank, the same numerical relations will exist. Although the drives to the shafts X64 and XI28 are identical, the shaft XI28 is coupled to have twice as great an effect upon the output shaft I08 as the shaft X64 has, and hence all of the differentials of the right-hand bank, as compared with the corresponding differentials of the left-hand bank, are multipled in effect by 2. A single revolution of the crank handle IOI transmitted through the gear I I2I will have 128 times the effect of a single revolution of the crankhandle transmitted through the gear II.

The rate controlling mechanism is designed to change the rate by unit steps, without gaps, from 1 to 255, all numbers being over the same common denominator whose value is unimportant since it can be changed in the output by any form of gearing or other uniform connecting train desired. a

In order to accomplish this result, the rate changing cams are so constructed, designed and operated that the gear II will be connected at alternate steps. The gear I2 will be disconnected for the first step and will thereafter be connected for two steps, then disconnected for two steps, and so on in continuous alternation. Similarly the gear I4 will be disconnected for the first three steps then connected and disconnected alternately throughout series of four successive steps. Gear 18 will come into operation at the eighth step, will remain connected for 8 steps then be disconnected for 8, and so on. The law governing the control of the other differentials is sufficiently indicated by these illustrations. It will be understood that the cam arrangement may be similar to that shown in Figs. 3 and 4 in which they are arranged in groups with suitable gearing between them.

The details of construction of the mechanism are illustrated in Figs. 13 and 14. Stationary shafts I26 and I21 support, respectively, shafts XI, X4, XI6 and X64 of the left hand bank and shafts X2, X8, X32 and XI28 of the right hand bank. The differential units are all alike and hence a description of one of them, as illustrated in Fig. 14, will suffice for all, it being understood that corresponding letters are applied to corresponding parts in all of the units but that the subscripts of the letters are made to correspond with the units in which the parts are used. The shaft XI 6 has fast upon it a sun gear $64. The hub of internal gear I64 is journalled upon the shaft XI6. The internal gear I64 is constantly in mesh with the transmission gear T64 which as already pointed out may be coupled to and uncoupled from the shaft I08 at will. An epicyclic or planet gear E64 is rotatably carried by an arm A64 integral with the shaft X64. The gears E84 and S64 are of equal diameters and have equal numbers of teeth. The gear I64 has an internal pitch diameter three times as great as the pitch diameter of the gear S64 and has three times the number of teeth of the gear S64. When the shaft X I6 is held stationary and the gear 164 is driven. one revolution of the gear I64 will produce 3, of

and hence of the II airmail shaft 22163. When the gear "fit is held stationary and the shaft XIS is driven one revolution of the shaft Xlt will produce of a revolution of the shaft Xii i. Since one revolution of gear 118 will produce revolution of the shaft Xl6 it will be seen that one revolution of the gear I16 will produce TF of a revolution of the shaft X64 as against the of a revolution produced by one revolution of the gear 164, the ratio of output through gear lit to output through gear I being as previously pointed out While the units have been referred to as all exact duplicates, it is to be noted that the sun gear Si is mounted upon a shaft X0 which is permanently held against rotation, and that the sun gear S2 is similarly mounted upon a shaft which is permanently held against rotation. it is also to be noted that the shaft X64 has fast upon its forward end an output gear 130 in place of the usual sun gear, and that the shaft Kim has fast upon its forward end an output gear MI in place of the usual sun gear.

The shafts lit and M1 are supported between frame members E32 and tilt. A suitable spacer sleeve tilt is interposed between the frame member ltd and the gear ass on the shaft i225 and afined to the shaft by a set screw 2135. A similar spacer sleeve H36 is interposed between the frame member 333 and the gear lfil upon the shaft i2! and amxed to the shaft by a set screw itl.

it will be rememberedthat the shaft m9 rotates in the opposite direction from the shaft me. in order that the output of shaft X64 may be additively combined with the output of shaft X628, a transmission pinion 238 is interposed between the'gear i330 and an output gear 539, while the gear l3! meshes directly with an output gear M0. The output gears Mil and E40 are arranged to drive the output shaft "39 through a differential gear I which is identical with the differential gears employed in the two banks of gears. The gear its is integral with a hollow shaft Xd which is journalled upon the output shaft "19 and which carries a sun gear Sd at its forward end. The gear H0 is fast upon the hub of an internal gear Id. An epicyclic or planet gear Ed is rotataloly carried by an arm Ad whose hub is fixed to the shaft M9 by means of a pin 142.

Having in mind that the effect of one revolution of the gear Id upon the shaft I09 when the gear Si is stationary would be to drive the shaft ")9 A of a revolution, where as the effect of one revolution of the shaft Xd while the gear Id is stationary would be to drive the shaft I09 through A of a revolution, it is evident that some provision must be made in the gear connections l3l, M0 and in the gear connections I30, I38, I39 for causing one revolution of the shaft XIZB to rotate the shaft I09 twice as far as one revolution of the shaft X64 rotates the shaft I09.

In the illustrative mechanism the gears are so chosen that one revolution of the shaft X64 produces it of a revolution of the shaft Kd thereby producing of a revolution of the shaft I09. The gears l3l and MD are so chosen that one revolution of the shaft XIZB produces of a revolution of the gear Id and hence of a revolution of the shaft I09. The value of the denominator is unimportant, the important point being that the ratios have common denominators and that their numerators are in the ratio of 2 to l.

While the drive ratio of 1-4 between successive differential units has been chosen herein and spoken of as illustrative, that ratio is regarded as excellently suited to the present purpose. As pointed out, the ratio must be greater than 2 to .1. 3 to 1 would be a suitable and operative ratio, but with the illustrative number and arrangement of the differentials, the differentials of the left hand bank instead of having relative values 14-16--64 would have relative values 1-3- 9-27 and the difierentlals of the right hand bank would have values 2-6-1844, which would only yield possible rates of driving speed running from 1 to 120 or less than one-half the range of the illustrative apparatus. With a ratio of 5 to i or any greater ratio, on the other hand, more than two banks of differentials would be required in order to avoid gaps in the series of possible ratios.

The principle of the invention is, however, regarded as comprehending a structure in which more than two banks of differentials are employed, as for example, a three bank machine in which successive diflerentials of a "bank bear the relation of 1-8 and in which the several banks have the relative weights of l to 2 to l, or a four bank machine in which the successive differentials of a bank bear the relation of i-ld and in which the several banks have the relative weights 'ofito2to4totandsoon.

I have described what i believe to be the best embodiments of my invention, I do not wish,

however, to be confined to the embodiments shown, but what I desire to cover by Letters Patent is set forth in the appended claims.

1 claim:

fl. Speed changing-mechanism; comprising a driving member; a driven member; a multiplicity of like differential gears intermediate said menubers arranged in a group and constantly coupled to one another in such manner that each differential of the group other than. the first receives the entire output of its predecessor in the group for reduction in a predetermined ratio and transmission to the driven member, whereby the individual output values of the dificrentials from the first to the last of thegroup are caused to form a geometrical series, and means for independently coupling the individual differentials selectively with the driving member in various combinations, to derive various speeds from said driving member and to deliver to said driven member a greatly multiplied range of resultant speeds, including means to compel the various possible ratios of input to output to be established in continuously ascending or continuously descending order.

2. Speed changing mechanism; comprising a driving member; a driven member; a multiplicity of like differential gears intermediate said members arranged in a group and constantly coupled to one another in such manner that each differential of the group other than the first receives the entire output of its predecessor in the group for reduction in a predetermined ratio and transmission :to the driven member, whereby the individual output values of the differentials from the first to the last of the group are caused to form a geometrical series, and means for independently coupling the individual differentials selectively with the driving member in various combinations, to derive various speeds from said driving member and to deliver to said driven member a greatly multiplied range of resultant speeds, including means to compel the various ratios of input to output to occur in a sequence forming an arithmetical series, and means to indicate visually the speed which is established.

3. Speed changing mechanism: comprising a driving member; a driven member; a multiplicity of like differential gears intermediate said members so connectedto one another that these individual output ratios form a geometrical series and adapted to be coupled selectively with said input member individually and in combinations with each other to derive various speeds from said driving member which form an unbroken arithmetical series, and selector means to effect selection and coupling of the particular gear or combination of gears required to deliver any desired rate of speed in the available range thereof, said selector means arranged to compel the various speeds to be established in continuously ascending or descending order and including a plurality of like cam units, each including a plurality of individual differential controlling cams, and Geneva carry-over means for operating one unit from the next, step by step.

4. Speed changing mechanism: comprising a driving member; a multiplicity of differential gear units, each unit including two input gears and an output gear; also a coupling gear in mesh with one of said input gears, and movable into and out of a coupled position with said driving member; a driven member; means for moving said coupling gears selectively to and from their coupling positions respectively; means for coupling said differential units to each other in predetermined order; and means for coupling their output gears to said driven member, thereby to effect the delivery to said driven member of a motion combining the motions impressed upon the several input gears, to yield any of a wide range of speeds available by the use of said differentials, and selector means to effect selection and coupling of the particular gear or combination of gears required to deliver any desired rate of speed in the available range thereof, said selector means arranged to compel the various speeds to be established in continuously ascending or descending order and including a plurality of like cam units, each including a plurality of individual differential controlling cams, and Geneva carry-over means for operating one unit from the next, step by step.

5. Speed changing mechanism: comprising a driving member; a multiplicity of differential gear units, each unit including two input gears and an output gear; also a coupling gear in mesh with one of said input gears, and movable into and out of a coupled position with said driving member, means for locking the coupling gear when it is disconnected from the driving member, a driven member; means for moving said coupling gears selectively to and from their coupling positions respectively; means for coupling said differential units to each other in predetermined order; and means for coupling their output gears to said driven member, thereby to effect the delivery to said driven member of motion combining the motions impressed upon the several input gears, to yield any of a Wide range of speeds available by the use of said differentials, said means for moving the coupling gears including means for urging the gears normally into coupling positiomand means acting positively to incapacitate said coupling gears selectively.

6. Speed changing mechanism: comprising a driving member; a multiplicity of differential gear units, each unit including two input gears and an output gear; also a coupling gear in mesh with one of said input gears, and movable into and out of a. position in which it is coupled with said driving member; a driven member; means for moving said coupling gears selectively to and from their coupling positions respectively; means for coupling said differential units to each other in predetermined order; and means for coupling their output gears to said driven member, thereby to effect the delivery to said driven member of a motion combining the motions impressed upon the several input gears. to yield any of a wide range of speeds available by the use of said differentials, a rocker for and to support each of said coupling gears individually, anda camshaft having a series of cam discs each engaged with one of said rockers.

7. Speed changing mechanism; comprising a driving member; a multiplicity of differential gear units, each unit including two input gears and an output gear; also a coupling gear in mesh with one of said input gears, and movable into and out of a position in which it is coupled with said driving member; a driven member; means for moving said coupling gears selectively to and from their coupling positions respectively; means for coupling said differential units to each other in predetermined order; and means for coupling their output gears to said driven member, thereby to effect the delivery to said driven member of a motion combining the motions impressed upon the several input gears, to yield any of a Wide range of speeds available by the use of said differentials, a rocker for and to support each of said coupling gears individually, and a cam-shaft having a cam disc engaged with each of said rockers, said cam-shaft having a star-wheel fixed thereon; and a detent to hold said star-wheel yieldingly in each position of each cam.

8. Speed changing mechanism: comprising a driving gear-shaft; a driven gear-shaft; a multi plicity of speed-changing gear units adapted to transmit motion from said driving shaft to the driven shaft, the individual outputs of said units forming a geometrical series, coupling members individual to said units and operable individually to and from effective positions, and a selector means including a cam shaft having a plurality of cams thereon, each individually controlling one of the gear units low in the scale of output values, an additional like cam shaft having like cams for controlling similarly related units higher in the scale of output values, and Geneva carry-over mechanism for operating the second cam shaft from the first after a plurality of steps of the first equal to the ratio of output values of gear units controlled by corresponding cams of the two shafts.

9. A selector mechanism for effecting changes of speed automatically throughout a wide range of available rates of speed deliverable at the driven member in a speed-changing mechanism of the class described; said selector mechanism comprising a plurality of cam units each comprising a plurality of cam devices co-axially disposed along a common axis and rotatable in unison, means for rotating the first unit, and carry-over mechanism for operating the second unit periodically from the first.

10. A selector mechanism for effecting changes of speed automatically throughout a wide range of available rates of speed deliverable at the driven member in a speed-changing mechanism of the class described; said selector mechanism comprising a series of cam units each comprising a plurality of cam devices co-axially disposed along a common axisand rotatable in unison,

means for rotating the first unit, carry-over plurality of cam devices rotatable in unison and co-axially disposed along a common axis, means for operating one of said units through a predetermined series of steps constituting a cycle independently of operation of any other unit, during which cycle the selector cam surfaces of said unit are made eifective, and means to operate another of the units periodically from the first through a similar cycle, but only one step for each cycle of the first, to make effective cam surfaces in more than one unit with a consequent selection of additional rates of speed throughout the entire available range of rates of speed, said selective operations being each a linear function of the simple rotation of the cam shaft.

12. A selector mechanism for effecting changes of speed automatically throughout a wide range of available rates of speed deliverable at the driven member in a speed-changing mechanism of the class described; said selector mechanism comprising a cam shaft carrying a multiplicity of cam devices co-axially disposed along a common axis and divided into at least two units, at least one of said units having a predetermined movement of rotation independently of any other unit, and during which movement one or more selected cam surfaces of said unit are made effective, and a locking member between each two adjacent groups, whereby the selector system is so controlled that only the group or groups anterior to each lock can be affected by rotation of the selector system prior to release of the looking member.

13. A selector mechanism for effecting changes of speed automatically throughout a wide range of available rates of speed deliverable at the driven member in a speed-changing mechanism of the class described; said selector mechanism comprising a cam shaft carrying a multiplicity of cam devices co-axially disposed'along a common axis and divided into at least two units of which at least one unit has a predetermined movement of rotation independently of any other unit, and during whichmovement one or more selected cam surfaces of said unit are made effective; and a locking member between each two adjacent groups, whereby the selector system is so controlled that only the group or groups anterior to each lock can be affected by rotation of the selector system prior to release of the locking member, and the release of each lock in its turn is effected by the normal, unidirectional rotation of the cam assembly.

14. A selector mechanism for effecting changes of speed automatically throughout a wide range of available rates of speed deliverable at the driven member in a speed-changing mechanism of the class described; said selector mechanism comprising a cam shaft carrying a, multiplicity of cam devices co-axially disposed along a common axis and divided into at least two units, with locks therebetween so that at least one unit has a predetermined movement of rotation independently of any other unit, and during which movement one or more selected cam surfaces of said unit are made effective, said locks being so disposed and arranged as to be operated in reverse upon backsetting of the cam assembly.

15. A selector mechanism for eifecting changes of speed automatically throughout a wide range of available rates of speed deliverable .at the driven member in a speed-changing mechanism of the class described; said selector mechanism comprising a cam shaft carrying a multiplicity of cam devices co-axially disposed along a common axis and, divided into at least two units of which at least one unit has a predetermined movement of rotation independently of any other unit, and during which movement one or more selected cam surfaces of said unit are made effective, one cam in each unit having a series of four high surfaces on its periphery, alternating with four low surfaces; another cam in each unit having two high surfaces and two low surfaces; and a third cam in each unit having one high surface and one low surface.

16. A selector mechanism for effecting changes of speed automatically throughout a wide range of available rates of speed deliverable at the driven member in a speed-changing mechanism of the class described; said selector mechanism comprising a cam shaft carrying a multiplicity of cam devices coaxially disposed along a common axis and divided into at least two units, at least one of said units having a predetermined movement of rotation independently of any other unit, and during which movement one or more selected cam surfaces of said unit are made effective, and means to couple a plurality of said units together to make effective cam surfaces in more than one unit, with of additional rates of speed throughout the entire available range of rates of speed, said coupling means each including a locking member, an interrupted gear associated with one of said locking devices on an early unit in the series, a complete gear on a later unit in the series, and a short shaft parallel with the cam shaft and having a pinion in mesh with said complete gear at all times, and having an interrupted gear complemental to the first-named interrupted gear, and a locking member complemental to the looking member on the unit.

17. Speed changing mechanism; comprising a driving shaft having peripheral pinion-gearmeans adapted to be meshed at a multiplicity of regions along its length by a series of carrier gears to be driven thereby; a driven shaft parallel with said driving shaft; a multiplicity of differential units associated with said driven shaft, and each including a spider mounted rotatably upon the driven shaft, each spider having a hub, with a pinion fixed on the hub and adapted to mesh with one of said carrier gears, and a second pinion fixed on the hub and spaced co-axially from said first pinion, a first planetary gear on said spider and adapted to track around one of said hub pinions, a second planetary gear on said spider meshing with said first planetary gear, a third pinion co-axialiy disposed relatively to said spider hub and the driven shaft, and in mesh with said second planetary gear, serving as a sun gear therefor, and a fourth pinion fixed upon the hub of said spider and adapted to drive said hub; a series of carrier gears of which one is always in mesh with said fourth pinion; and a selector means adapted to move each carrier gear into and out of mesh with said corresponding a consequent selection fourth pinion; each differential unit having its the input to the output member comprising series above-named components so disposed that when of difl'erential gears arranged in two banks, means said fourth pinion is rotated by its carrier it for establishing a driving connection between the supplies an input of predetermined rate to the input member and each diflerential independdriven shaft system, acting through the third ently of the other diflerentials, the output ratios pinion upon the first planetary gear, then upon of the individual differentials 01' each bank form-- the second planetary gear, to cause said second ing a geometrical series, each bank including out planetary gear to track upon a fifth pinion and put means combining the outputs of all the thus to rotate the spider, each spider acting to differentials of the bank and connections beimpart to the primary input pinion of a posterior tween the banks and the output member for or succeeding differential in the system an input additively combining the outputs of the banks which is the resultant oi the combined motions and for causing the output 01' one bank to be of the preceding diilerentials in the series, the transmitted to the output member in a definite pinion which serves as the track for the second ratio and the output of the other bank to be planetary gear of the first differential being fixed transmitted to the output shaft in double that against rotation, and the last spider of the series ratio, and means connecting each diflerential being fixed upon the driven shaft. gear of each bank other than the first to be driven A Speed Changing mec n fi p by its predecessor in the bank in the ratio of an input member, an output member, and means 1 to 4.

independently of the other differentials, the outconnections between the banks and the output put ratios of the individual diflerentials of each member for additively combining the outputs of bank forming a geometrical series, each bank inthe banks and for causing the output of one bank cluding output means combining the outputs of to be transmitted to the output member in a all the diflerentials of the bank and connections definite ratio and the output of the other bank 19. A speed changing mechanism comprising mined ratio. an input member, an output member, and means 22. A speed changing mechanism comprising for selectively controlling the driving ratio from an input member, an output member, and'a rate the input to the output member comprising series changing member for controlling the rate 01' outential independently oi. the other difi'erentials, gears arranged in two parallel banks and all the output ratios of the individual dlflerentials connected to operate the output member, a pair of each bank forming a geometrical series, each of parallel driving shafts connected to be operated bank includingioutput means combining the outinvariably by the input member and disposed puts of slime difl'erentials of the bank and conadjacent the respective banks of difierential nectionsbetween the banks and the output memgears, and means for selectively connecting the be transmitted to the output member in double rate changing member, and connection conthat ratio.

20. A speed changing mechanism comprising shatts. an input member, an output member, and means PETER J. McLAREN. for selectively controlling the driving ratio from trolling members carried by said controlling 

